HOLDEN, Maine — The investigation into what caused a collision on busy Route 1A Friday morning and sent three people to the hospital with serious injuries remained under investigation Friday night, according to police.

The crash that snarled traffic involved a 2003 Chevrolet Sierra pickup truck and a 2005 Ford Taurus station wagon and occurred around 9 a.m., just west of the town office, according to Holden police Sgt. Eugene Fizell.

The pickup, driven by Joshua Soper, 30, of Dedham, was traveling east toward Ellsworth when it struck the westbound Ford, driven by Sigrid Madigan, 73, of Dedham. Dawn Light, 31, of Liberty was a passenger in Soper’s truck.

All three were transported to Eastern Maine Medical Center in Bangor.

Fizell said the pickup was in the far westbound lane traveling in the wrong direction at the time of the crash. Two other drivers avoided crashes with Soper before he hit Madigan’s car head-on.

“That becomes a question we need to answer,” said Fizell, who added that speed is not believed to be a factor, as traffic was bumper to bumper in both directions.

The sergeant said Friday evening he believed Soper was traveling at about 40 mph at the time of the crash. He said the results from the blood-alcohol test to determine whether Soper was driving while intoxicated were not yet available.

No charges have been filed in connection with the crash, but the investigation into its cause is ongoing, Fizell said.

Fizell said Light, who was in the intensive care unit Friday night, suffered a large laceration across her forehead and fractured an ankle.

Madigan fractured her pelvis, an ankle and several ribs, he said. Soper fractured a hip and suffered facial trauma.

Fizell said given the traffic volume, with many vehicles traveling to Acadia National Park and Bar Harbor and westbound cars likely traveling to Bangor for this weekend’s American Folk Festival, police are fortunate things did not end up worse.

“This could’ve been a very different scenario,” he said. “As bad as it is, it’s not as bad as [some of] the accidents we’ve had in the region. We’re very lucky there weren’t more vehicles involved and more people hurt.”

Three people died in a two-vehicle collision on Route 1A in Dedham on Aug. 5.

Route 1A, the main highway between the Bangor area and Acadia National Park, was closed for much of Friday morning while Maine State Police reconstructed the accident. The road reopened Friday afternoon, according to the Maine Department of Transportation.